What is a .un~ file or or why does Vim in the Terminal make the .un~ file?

Question

I've noticed I have some dotfiles that end with .un~, for example I have a .vividchalk.vim.un~, but I'm not sure where that came from. It seems like they are created when I use Vim in the Terminal. What are these files? Can have them remove themselves when I close the file I'm editing?

Answer 1

When you edit and save files, Vim creates a file with the same name as the original file and an un~ extension at the end.

Vim 7.3 contains a new feature persistent undo, that is, undo information won't be lost when quitting Vim and be stored in a file that ends with .un~. You have set the undofile option, so Vim creates an undo file when saving the original file. You can stop Vim from creating the backup file, by clearing the option:

:set noundofile

Note that, by default this option is turned off. You have explicitly enabled the undofile option in one of the initialization files. If you want your undofiles to be stored only in a particular directory, you can point the undodir option to a directory that will contain all your aggregated undofiles.

Source: http://vimhelp.appspot.com/vim_faq.txt.html#faq-7.2